fix tests for Ruby Enterprise Edition?

spec/spec_helper.rb

@@ -29,7 +29,7 @@
     # ...rather than:
     #     # => "be bigger than 2"
     expectations.include_chain_clauses_in_custom_matcher_descriptions = true
-  end
+  end if RUBY_VERSION >= '1.9'
 
   # rspec-mocks config goes here. You can use an alternate test double
   # library (such as bogus or mocha) by changing the `mock_with` option here.